UIColor initialise with hexadecimal string like "#ABCDEF"

UIColor+HexString.swift

import UIKit

extension UIColor {

    convenience init(hexaString: String, alpha: CGFloat = 1) {
        let chars = Array(hexaString)
        self.init(red:   CGFloat(strtoul(String(chars[1...2]), nil, 16))/255,
                  green: CGFloat(strtoul(String(chars[3...4]), nil, 16))/255,
                  blue:  CGFloat(strtoul(String(chars[5...6]), nil, 16))/255,
                  alpha: alpha)
    }
}